A pressurized container usually contains a product together with a propellant. The propellant usually creates the necessary pressure inside the container. The propellant may be a liquid or a gaseous propellant. When the propellant is a liquid propellant, the pressure inside the container is created by the vapor pressure of the liquid propellant. The gaseous propellant and the vapor phase of the liquid propellant are usually located in the headspace of the container when the container stands in its upright position. The pressure inside the container is higher than the normal outside atmospheric pressure. The inside pressure of the container is maintained by closing the container with a valve. Consequently, the propellant tends to exit from the inside of the container once the valve of the container is opened. Thereby, the propellant also drives the product out of the container.
In order that all of the product can be expelled out of the container it has to be ensured that enough propellant is available in the container with respect to the amount of product. Consequently, it has to be ensured that the propellant is not allowed to exit unnecessarily, i.e. the product must be expelled at the same time as the propellant. If product is not expelled at the same time as the propellant, the propellant may be progressively emptied out of the pressurized container until the remaining amount of propellant may become too low with respect to the rest of product remaining in the container to ensure the complete dispensing of the rest of product from inside the pressurized container. The rest of the product which cannot be expelled from inside the pressurized container is then wasted. Other possible drawbacks of propellant exiting unnecessarily from the container are deterioration of the characteristics of the expelled product. For example, when the product is a foaming product, the density of the foam may increase in an undesirable manner.
The discharge of propellant without product may happen whenever the product is not placed between the propellant and the discharge orifice of the pressurized container. Indeed, it has to be ensured that the propellant is obliged to pass through the product, pushing at least part of the product out of the pressurized container. This undesirable positioning of the propellant with respect to the product and the discharge orifice of the pressurized container may be reached when the pressurized container is allowed to discharge while the container is rotated from the desired discharge position.
For example, when the pressurized container comprises a dip tube connecting the discharge orifice at the top of the container with the inside of the pressurized container, the undesired direction would be to invert the pressurized container, i.e. to turn it upside down. In this position the gaseous propellant in the headspace is capable of escaping directly from the inside of the container through the dip tube without pushing the product through the dip tube. By contrast, when the pressurized container does not include a dip tube, the undesired direction would be when the container is not inverted, i.e. the container is held upright. This substantially upright position leads to the escape of gaseous propellant from the inside of the container, because the product is not positioned between the discharging opening and the propellant. In both cases this leads to the escape of propellant from the inside of the container without any corresponding expulsion of product, resulting in the corresponding drawbacks as discussed above.
It is well known in the industry making pressurized containers that there is a need to provide the pressurized containers with a blocking mechanism which prevents the opening of the pressurized container when the pressurized container is in an undesired orientation. WO-91/03 408 and WO-95/06 606 describe blocking mechanisms, e.g., in form of a ball, located inside the pressurized container so as to block the discharge orifice of the pressurized container when the pressurized container is in an undesired orientation. In the prior art, the blocking mechanism is in direct contact with the product and the propellant during the discharging flow when the valve of the pressurized container is opened.
It has been found that the blocking mechanism positioned in this way in the discharging flow only works for low discharging rates of about 2 grams of product per second as the maximum limit. Indeed, the discharging rate has to be low enough such that the blocking means, e.g. the ball, is not dragged in the product and/or propellant flow. Otherwise the blocking means may be pushed by the discharging product and/or propellant into the blocking position of the valve even when the valve is oriented in the correct position. Therefore, it would be preferable to have a blocking mechanism separated from the discharging flow of the product and/or the propellant.
A blocking mechanism which is separated from the discharging flow of the product and/or of the propellant is, for example, described in U.S. Pat. No. 3,186,605. Thus patent describes a valve comprising a blocking mechanism along a side of a valve stem. The blocking means comprises a circular transverse wall member, a circular plate and a non-compressible ball. The transverse wall member and the circular plate are rigidly connected to each other. The non-compressible ball is placed between the transverse wall member and the circular plate. The circular plate is smaller in diameter than the transverse wall member. To open the valve, the transverse wall member has to slide axially within the valve chamber towards a transverse shelf wall. The valve is free to be opened when the ball remains within the diameter of the circular plate. The valve is blocked when the ball rolls away from the circular plate onto the transverse shelf wall, since the transverse wall member is not prevented by the non-compressible ball from sliding towards the transverse shelf wall.
However this valve is quite bulky, since the overall diameter of the valve is increased by the transverse wall member and the valve chamber with respect to standard valves for standard pressurized containers. Furthermore, the part of the valve comprising the blocking mechanism is located on one side of the valve stem. Consequently, the container needs to have a wider opening to allow the insertion of this valve into the container with respect to usual valves, i.e., the containers in which to insert this valve of '605 have to be specially adapted and made. This increases also the manufacturing costs of a container with this kind of valve.
Another type of blocking mechanism is described in WO-89/10881, FR-A-2 637 870 and EP-A-0 526 298. The blocking mechanism is now located within the nozzle outside the pressurized container. It has been found that having the blocking mechanism in the nozzle limits the form and the dimension of the nozzle itself. Indeed, the nozzle has to be constructed in such a manner that it allows the functioning of the blocking mechanism. Furthermore, it has been found that such a specific nozzle comprising the blocking means has an increased cost with respect to usual nozzles available on the market. This means that when the blocking mechanism is not part of the valve, only specific, usually not cost effective nozzles can be used.
A further type of blocking mechanism is shown in British Pat. No. 1,470,013. As with several mechanisms of the prior art, in the British patent, the product flows through the blocking mechanism.
In pending European Patent Application No. EP-A-0811 563, published on Dec. 10, 1997, there is a valve blocking mechanism described wherein the blocking mechanism preventing the opening of the valve when the discharge orifice of the valve is in an undesired orientation, is separated from the discharging flow of the discharging product and/or propellant from inside the pressurized container when the valve is in an open position, allowing the use of any cost effective nozzle available on the market and having dimensions which allow the application of the valve of said patent application to conventional containers.
In the invention of said European patent application there is a valve comprising a stem, a housing, and a blocking means. The stem is movable within the housing to allow the opening and the closing of the valve. The stem comprises a discharge orifice connected to a discharge conduit. The discharge conduit is located on one end of the stem. The stem is free to move reciprocally within the housing. The blocking mechanism is situated within the housing and acts to block the movement of the stem within the housing when a container bearing the aforedescribed valve is in an undesired position. European Patent Application No. EP-A-0 811 563 is incorporated by reference herein and made a part of the disclosure of this invention.
As noted earlier, an aerosol valve is a multi-component structure that must be molded and assembled. Aerosol valves are also mass-produced items. Any decrease in the number of molding and/or assembly operations affords a considerable economic advantage to the valve manufacturer. It is one object of this invention to mass-produce the blocking valve of this invention in a cost effective manner.